Mobile Chedar

1
Mobile Chedar A Peer-to-Peer Middleware for
Mobile Devices Presentation for International
Workshop on Mobile Peer-to-Peer Computing
(MP2P05)

• 12.3.2005
• Niko Kotilainen, research assistant
• Department of Mathematical Information Technology
• University of Jyväskylä, Finland
• http//tisu.it.jyu.fi/cheesefactory
• With co-authors Matthieu Weber, Mikko Vapa and
  Jarkko Vuori

2
Overview

• This paper describes Mobile Chedar, which is an
  implementation of a mobile peer-to-peer
  middleware enabling information sharing in a
  mobile environment
• The proposed middleware is an extension to a
  non-mobile Chedar P2P network
• Mobile Chedar allows Bluetooth-enabled mobile
  devices to access resources of Chedar P2P network
  through Chedar gateway nodes (workstations with
  Bluetooth adapters)
• The middleware can be used to construct mobile
  peer-to-peer applications and as an example of
  such applications a co-operative learning
  application using Mobile Chedar is presented

3
Related Work

• Four different MP2P middleware propositions were
  identified as the closest related work
• Proem, 7DS, XMIDDLE and MOBY
• In contrast to these middlewares, Mobile Chedar
  is an extension to existing peer-to-peer network
  and therefore differs in the approach
• Also, Mobile Chedar provides mechanisms for data
  streaming, whereas the considered middlewares are
  designed for disseminating rather static content
• The implementation of Mobile Chedar relies on
  Bluetooth, whereas many of the others have been
  built on Wireless LAN technology

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Chedar

• Chedar (CHEap Distributed ARchitecture) is a
  peer-to-peer middleware designed for peer-to-peer
  applications
• For example Chedar can be used to locate idle
  computers with a given characteristics in order
  to run computationally intensive calculations
• Programmed with Java 2 Standard Edition using TCP
  sockets
• Currently used for speeding up the computations
  of NeuroSearch resource discovery algorithm with
  Peer-to-Peer Distributed Computing application
  (P2PDisCo) and for studying distributed data
  fusion in peer-to-peer environment

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Chedar Internals

• Nodes maintain a database of locally available
  resources and metadata for the resources such as
  type and path for a file or description of
  application registered as a resource
• Resource database is stored as an XML document
  using a specific DTD, which allows making rich
  and complex queries to the database in the form
  of XPath expressions
• Each Chedar node is identified with a unique
  identifier

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Mobile Chedar

• With the advent of mobile computing and the
  inherent peer-to-peer properties of mobile ad hoc
  networks, Chedar has been extended to Mobile
  Chedar for mobile devices
• Mobile Chedar provides functionalities for
  registering resources on a mobile device and for
  querying resources from other peers
• Using Mobile Chedar, mobile devices can for
  example locate a communication stream from the
  network and subscribe to that stream to get all
  data written to the stream
• By publishing the stream further other peers can
  join the stream
• Programmed with Java 2 Micro Edition using
  Bluetooth transmission technology

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Restrictions of Bluetooth

• Because of restrictions in Bluetooth, one node
  can be connected to only one piconet at a time
  forcing the connection topology to be star-shaped
• Chedar / Mobile Chedar gateway node can be for
  example workstation with a Bluetooth adapter and
  an Internet connection

Mobile Chedar
Mobile Chedar
Mobile Chedar
BT
BT
Chedar P2P Network
BT
Mobile Chedar
Chedar / Mobile Chedar gateway
BT
BT
BT
Mobile Chedar
TCP
Mobile Chedar
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Streamable Resources

• Nodes can provide streamable resources to other
  peers and subscribe to these streams
• Multiple peers can simultaneously subscribe to
  the same stream and after subscribing they also
  start publishing the stream
• Because streams are duplex, the data written to
  the streams by peers will be delivered to all
  other peers currently subscribed
• However, the order of the data is not preserved
  and it is handled in a First-In-First-Out manner

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Stream Delivery
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Neighbor and Resource Discovery

• Neighbor discovery is a prerequisite for resource
  queries
• Using Bluetooths Service Discovery Protocol
  (SDP) all nodes within range of the radio
  frequency transceiver can be detected
• Discovery of resources is performed as one hop
  query tagged with a unique Message-ID to all the
  nodes within Bluetooth range
• When a query arrives to Chedar/Mobile Chedar
  gateway node, it forwards the query to all of its
  Chedar neighbors with default time-to-live

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Mobile Chedar Application Programming Interface

• Mobile Chedar provides the following API for MP2P
  applications
• MP2P applications must implement the following
  methods

register(String resourceidentifier) Adds a
resource to the resource database. unregister
(String resourceidentifier) Removes a resource
from the resource database. connected() Chec
ks if Mobile Chedar is connected to other
Chedar nodes. query(String resourceidentifier) Ex
ecutes a query. subscribe(Resource
resource) Subscribes to the found
resource. unsubscribe(Resource
resource) Unsubscribes from a subscribed
resource. send(Resource resource, Message
data) Sends data to the subscribed resource.
resourceFound(Resource resource) Informs the
application when the query has located a
matching resource. receive(Resource resource,
Message data) Informs the application when new
data has arrived to a subscribed resource.
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Mobile Peer-to-Peer Learning Environment

• Mobile Peer-to-Peer Learning Environment (MP2PLE)
  is designed for collaborative note taking during
  lectures as a test application for Chedar
  peer-to-peer network and Mobile Chedar middleware
• MP2PLE user interface contains a text area
  displaying the current state of notes and
  provides means for users to edit them
• The user is allowed to modify any part of the
  notes by selecting a paragraph and submitting the
  changes
• Whenever the data is being changed it is streamed
  to other participants subscribed to the same
  stream

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MP2PLE User Interface
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Use Cases for MP2PLE

• There are two common use cases for such kind of
  an application
• Firstly, it serves as a personal note-taking tool
  to store lecture notes
• Secondly, people who do not take notes can
  benefit from other users notes, either during
  the lectures, or later, e.g. from home by
  accessing Mobile Chedar nodes through a gateway
  node

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Limitations of MP2PLE

• Tiny user interface is problematic and provides
  only primitive means to take notes e.g., pictures
  cannot be drawn and class presentation material
  cannot be integrated with MP2PLE
• Also, taking lecture notes is difficult because
  of the small keypads in mobile phones
• Bluetooth does not allow multi-hop with current
  mobile phones, because the device can only belong
  to one piconet at a time

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Conclusion and Future Work

• Mobile peer-to-peer enables new kind of
  applications taking advantage of emerging
  short-range radio technologies and allowing
  collaborative resource sharing between peers
• This paper described one way to construct
  peer-to-peer networks with support for mobile
  devices and demonstrates the feasibility with a
  prototype implementation
• The future work of Mobile Chedar and MP2PLE
  includes the support of audio and video streams
  and determining the feasibility of the approach
  with practical experiments

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Thank You!

• Any questions?